1. Field of the Invention
The present invention relates to a damper pulley, and more particularly to a damper pulley which is lightweight and can be produced in a simple manner.
2. Background and Description of Related Art
FIG. 5 illustrates a conventional damper pulley. As shown, the pulley includes a cylindrical boss portion 1, to be fixed onto a rotary shaft (not shown), and an annular main portion 2, which is positioned about the outer periphery of the cylindrical boss portion 1. Such pulleys were integrally formed by casting. A rubber or elastic member 4 is joined to the outer periphery of the main portion 2, and a ring-shaped belt retaining portion 3 is fit over the outer periphery of the rubber or elastic member.
A rotary driving-force from the rotary shaft is exerted from the belt retaining portion 3 to a belt 5 through the rubber or elastic member 4. When torsional vibrations are exerted from the rotary shaft, the belt retaining portion 3 resonates therewith, thereby absorbing or restraining the exerted torsional vibrations.
However, a damper pulley formed of cast metal has thick dimensions and, accordingly, has substantial weight. The conventional process also requires cure-bonding with adhesives of the rubber or elastic member 4, which increases production costs. In this case, if bonding is not used, the rubber or elastic member 4 slips in the rotary direction, and further, when it is very hard, the rotary force may not be exerted.
Japanese Utility Model application laid-open No. Sho 63-37841 discloses a damper pulley which has grooves in the outer peripheral surface of the main portion and the inner peripheral surface of the belt retaining portion, and a part of the rubber or elastic member is inserted so as to fill the grooves thereof in order to prevent slipping. However, it requires forming grooves and inserting the rubber or elastic member is difficult.